This invention relates to an annular cutting die for shaving metal rods or bar stock of the type disclosed in U.S. Pat. No. 2,233,928, issued Mar. 4, 1941, and comprises an improvement in such annular cutting dies, and also an improved method of circumferentially shaving or cutting away the peripheral surface portions from metal rods or bar stock.
Annular cutting dies of the type to which this invention relates are used to cut or shave away the peripheral surface portions from metal rods or bar stock thereby to provide such rods or bars with clean surfaces free of oxides or other contaminants and thus better prepared for subsequent processing, such as in the manufacture of wire for electrical conductors as set forth in the aforesaid U.S. Pat. No. 2,233,928, or for the preparation of core or seed rod for continuous metal casting operations such as disclosed in U.S. Pat. No. 3,060,054, and related U.S. patents.
In that this invention comprises improvements in the apparatus and method disclosed in the aforesaid U.S. patents, the disclosures of said U.S. Pat. Nos. 2,233,928 and 3,060,054 are expressly incorporated herein by reference.
Prior art annular cutting dies for this service, such as those shown in U.S. Pat. No. 2,233,928, were designed and constructed with six, or possibly more, facets or surface portions of distinctive geometric planes formed within the conical face or outer annular tapered surface or side of the annular cutting blade, which in turn provided six, or more, approximately equally spaced radially extending cutting edges about the annular cutting blade. The six facet annular die in its designed mode of operation of circumferentially cutting or shaving away the peripheral surface portion from around a metal rod or bar while such rod or bar is moving continuously through the annular die, has been found not to be stable or consistent in its performance, due apparently to uneven rates of wear, among other disadvantages in its use. Specifically, the conventional prior art six facet annular cutting die in operation initially splits the peripheral surface portion which is being, or has been, circumferentially cut or shaved away from the rod or bar into three discrete longitudinal sections or shavings that are each in the shape or configuration of an adjoined or double arcuate unit or portion in cross section, such as shown in FIG. 3 of the drawing.
However, as the six facet annular die wears due to use, the changing dimensions or configuration of the die working areas appear to cause one or more of the said adjoined or double arcuate units or portions of the original three longitudinal sections or shavings, to splinter or break into two individual arcuate units or strips whereby the cutting or shaving operation then proceeds with the circumferential cut or shaved away peripheral surface portion thereafter being separated into four, or five, or six, arcuate longitudinal sections or shavings in an irregular and uncontrollable sequence. Furthermore, the three longitudinal sections or shavings of a double or adjoined arcuate unit or portion, which are initially produced by the six faceted annular die from the circumferentially cut or shaved away peripheral surface portion of the rod, each assume an individual direction or angle of movement or egress away from the cutting edge of the blade of the annular cutting die and travel therefrom over the outer face of the blade. These assumed paths or courses of travel as the cut away sections or shavings move away from the blade of the cutting die introduce and establish areas or patterns of abrasion and in turn cause wear or erosion in the annular cutting die, which conditions adversely influence the rates and unevenness of wear therein. The subsequent splintering or breaking of one or more of the said initial three longitudinal double arcuate sections or shavings derived from the circumferentially cut away peripheral surface portion into two fragments of individual arcuate units or portions often results in one of the separated arcuate units of portions assuming a different direction or angle of movement or egress away from the cutting edge of the blade of the annular die and over the outer face of the blade. This diversion of a path of travel of the splintered or separated arcuate unit or units and its new pattern of abrasion appears to accelerate the degree of unevenness of wear or erosion as well as the rate of wear.